vendor/xz/5.2.5vendor/xz

1 files changed, 6 insertions, 2 deletions

diff --git a/src/liblzma/common/common.c b/src/liblzma/common/common.c
index 57e3f8ebd62a..cf714e5e43b4 100644
--- a/src/liblzma/common/common.c
+++ b/src/liblzma/common/common.c
@@ -1,6 +1,6 @@
 ///////////////////////////////////////////////////////////////////////////////
 //
-/// \file       common.h
+/// \file       common.c
 /// \brief      Common functions needed in many places in liblzma
 //
 //  Author:     Lasse Collin
@@ -99,7 +99,11 @@ lzma_bufcpy(const uint8_t *restrict in, size_t *restrict in_pos,
 	const size_t out_avail = out_size - *out_pos;
 	const size_t copy_size = my_min(in_avail, out_avail);
 
-	memcpy(out + *out_pos, in + *in_pos, copy_size);
+	// Call memcpy() only if there is something to copy. If there is
+	// nothing to copy, in or out might be NULL and then the memcpy()
+	// call would trigger undefined behavior.
+	if (copy_size > 0)
+		memcpy(out + *out_pos, in + *in_pos, copy_size);
 
 	*in_pos += copy_size;
 	*out_pos += copy_size;